This invention relates to electrical wiring devices, and particularly to receptacles having four outlets and incorporating a surge suppression circuit that protects each of the outlets.
Wiley U.S. Pat. No. 4,583,799, Apr. 22, 1986, discloses an example of a multiple (four) outlet receptacle of a type to be improved by the present invention to incorporate, in addition to the otherwise present elements, a surge suppression circuit. The receptacle as earlier disclosed comprises a relatively shallow insulating housing with contacts for four outlets arranged in respective quadrants of the housing and is designed for mounting on a surface flush with the back of the housing. The earlier device has been further improved and also provided with additional mounting accessories, such as disclosed in copending application Ser. No. 340,198, filed Apr. 19, 1989 by Wiley et al., and assigned to the assignee of the present invention. The receptacle has proven very satisfactory and has enjoyed considerable success. It provides four outlets in a neat and trim configuration. Since angle plugs may be used which have their cords leading in four different orthogonally related directions, cord confusion and the unattractiveness of a jumble of cords is minimized.
It is now a desire to improve upon the former design by incorporating within such receptacle, without basically altering its neat and trim appearance, a surge suppression circuit so that each of the outlets is protected against voltage surges which could endanger equipment connected to them. One suitable surge suppression circuit is that disclosed in copending application Ser. No. 345,929, May 1, 1989 by Misencik et al. which offers advantages because of features that allow the elements of the circuit to be compactly arranged. By the present invention, a multiple (at least three, preferably four as will be described) outlet receptacle is provided with a molded insulating housing suitable for mounting to a surface and having contact elements therein, the housing front face having plug blade receiving apertures for each of the four outlets arranged in respective quadrants of the front face and the housing having a back surface with wire terminals and with a surge suppression circuit including at least one surge suppressor such as a metal oxide varistor connected with the internal contact elements and located within the same housing among and between the various contact elements. In a specific embodiment of the invention, the surge suppressor is a substantially disk shaped element that is physically arranged substantially on edge between the front and back faces of the housing and, further, with the back face having a bowed-out portion to accommodate part of the varistor. The bowed-out portion, in one embodiment, extends outwardly from the major portion of the back face no more than about the same extent as the raised ribs that locate the ground plate. As with the prior disclosed receptacle, a specific embodiment of the invention may have the contact elements attached to respective conductive plates of which one is an apertured ring and the other is disposed therein; the centrally located conductive plate has an opening through which the varistor extends. The opening in the conductive plate and the bowed-out portion of the back plate allow use of a larger varistor than would otherwise be feasible while keeping to the shallow dimensions of the receptacle as are desired. Other elements of the surge suppression circuit, in the specific embodiment, include a fuse and various resistors that are physically associated with the ring-like conductive plate. Another feature of the surge suppression unit is to have one or more indicating elements for indicating the condition of the surge suppression circuit which are visible from the front surface such as by first and second light emitting devices indicating respectively that power is on and surge suppression is lost or that power is on and surge suppression is present. These are conveniently arranged for high readability at substantially opposite extremes of the housing front face.
The invention can also be applied to equip a receptacle of the type described with status indication even without surge suppression. That is, an indicating element can be connected as a pilot light between the contact plates for indication of power being present.
Other features of the invention will be subsequently described herein and will make apparent to those skilled in the art alternative arrangements consistent with the more general aspects of the present invention.